Vertically expandable carry bag and cinching structure for same

ABSTRACT

A carry bag and a cinching structure for use with a carry bag of the type having a shell with a predetermined maximum vertical rise. A channel connected to the shell seats a first portion of an elongated strap therein. A second portion is exposed from the channel. The strap is moveable with respect to the channel thereby causing the shell to cinch and the bag to assume a vertically constrained size while a carry strap increases in size. A cinching structure comprises the cooperation of the channel and the strap (webbing) and their materials and relative dimensions, free of any further hardware due, to vertically constrain the size of the bag. Optionally, the carry strap has an adjustable length to meet the needs of users of various height and having differing notions of how to wear the bag on their bodies.

CROSS REFERENCE TO RELATED CASES

This is a continuation-in-part of U.S. application Ser. No. 10/424,469, filed on Apr. 28, 2003, entitled “Vertically Expandable Bag,” now issued as U.S. Pat. No. 7,073,942 on Jul. 11, 2006, which is a continuation-in-part of U.S. application Ser. No. 09/782,627, filed Feb. 13, 2001, now abandoned, which is a continuation-in-part of Design Application No. 29/106,466, filed Jun. 15, 1999, entitled “Bag With Variable Gathers,” now issued as U.S. Pat. No. D437,481, which is a continuation in part of Design Application No. 29/094,412, filed Oct. 1, 1998, entitled “Scrunch Bag,” now abandoned. This application is also a continuation-in-part of U.S. Application Serial No. 29/169,217, filed Oct. 16, 2002 entitled “Variable Volume Tubular Bag,” now issued as U.S. Pat. No. D 482,197, which is a division of U.S. Application Serial No. 29/137,117, filed Feb. 13, 2001, entitled “Tubular Bag With Variable Gathers,” now issued as U.S. Pat. No. D 473,374, which is also a continuation-in-part of the aforesaid Ser. No. 29/106,466 application. Each of the foregoing applications is hereby incorporated by reference as if set forth in their respective entireties herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a bag and cinching structures that enable a vertical dimension to readily change while the bag is in use to accommodate a great many different height users as well as the carry needs of such users, free of external hardware or devices.

2. Discussion of the Related Art

Various bags in accordance with the prior art are illustrated in FIGS. 1-4. For example, FIG. 1 illustrates a conventional backpack in which cinching is done by varying a length of webbing 106 through a system of sliders 108. The webbing 106 is on the exterior of the backpack and the ends are sewn into the panel seams 109. Also cinching of the backpack can be accomplished by draw cords 110 on the exterior of the backpack that are channeled through fabric strips 111 folded over onto themselves and stitched into the panel seams 109. The draw cords are held in place by a cord lock 112.

FIG. 2 illustrates a conventional drawstring pouch 102 which is closed by pulling a draw cord 110 through a neck 113 of the pouch. The neck 113 of this pouch comprises an upper edge of the fabric of the pouch folded over onto itself and stitched to thereby define a tunnel for the draw cord 110 to pass through. The draw cord is cinched by a cord lock 112, but the vertical rise of the pouch is not effected.

FIG. 3. illustrates a conventional tote 104 having a handle 116 affixed to the top for carrying by a user. The tote includes a zipper 120 that is arranged to release a gusset 118 that circumscribes the width of the tote. Typically, the tote is put down and then unzipped to expose a panel of material that will lengthen the exterior. When released, as shown in FIG. 4, the length of the bag is increased by the size of the gusset 118, while the relationship of the handle 116 to the tote 104 remains unchanged. To shorten the bag once again, the zipper puller must be manually aligned with the zipper teeth.

Common to the designs of FIGS. 1-4 is a mechanism for adjusting the volume or access to the bags in a specific way; however, bag designers have not been attentive to the vertical component of carry bags, which is a critical component if the needs of a range of users is to be accommodated. It has been posited that ninety percent of the adult human female population is within eight inches of a median height, yet the sixteen inch variation among such persons is quite difficult to accommodate with a universal bag. Because of different human heights in the target audience, the vertical length of a bag has been a determining factor in selecting a bag to purchase, use, and also in governing how a user can carry the bag (when considered in combination with the carry strap).

What is needed in the art are improvements in bags that readily accommodate, among other things, differences in body heights and differences in preferred carry methods while the bag is in use.

Also, because of the proliferation of retail stores and credit cards in the last 20 years, today's shoppers are more spontaneous in their buying behaviors. A re-usable carry bag that allows for easy handling and has a variable volume transport capacity is highly desirable.

In general, all successful bags have structural integrity, retaining their shape when in use to easily receive and discharge contents. This feature is especially important at the bag's aperture for viewing contents inside without difficulty. Additionally, all successful carry bags possess a level of carrying comfort and provide trouble-free access to articles inside while the carry bag is on the body.

However, what remains needed in the art is a carry bag with all of the attributes mentioned above plus the added advantage of easily and quickly changing its transport volume as the shoppers' needs arises. Furthermore the changes in the bag's capacity volume should be independent of the weight or volume of its contents enabling the user more choices of preferred shape. Also the bag's vertical adjustments should not depend on whether the bag is open or closed, or even closable, allowing the user more handling choices. Lastly what is most desirable is an expandable carry bag that is a simple to operate without the complexity and additional costs of extra hardware and or external devices to support the carry bag's structural integrity at different vertical rises.

The present invention addresses these and other needs in the art.

SUMMARY OF THE INVENTION

In one aspect, the present invention relates to a vertically expandable bag which includes a shell having a lower margin and an upper margin spaced from the lower margin by a predetermined vertical rise of material. The shell defines an interior space for receiving items. A channel is defined along the predetermined vertical rise of material of the shell. There is an elongated strap having a first portion disposed within the channel and a second portion exposed from the channel and defining a carry strap for handling by a user. The channel cinches the material of the shell along the predetermined vertical rise thereof as the upper margin is slid along the first portion of the strap toward the lower margin of the shell while the second portion of the strap defining the carry strap increases in length. Any gathers in the shell are released and the predetermined vertical rise is at least partially restored as the upper margin is slid along the second portion of the elongated strap.

A cinching mechanism in accordance with the invention is combined with a carry handle to provide a universally adaptable bag for an expanded number of uses and persons as compared to prior art constructions. The cinching mechanism can operate independent of any closure mechanism, such that a carry bag constructed in accordance with the invention can be constrained to assume a vertically constrained size regardless of whether the bag is in an open or closed state. Consequently, articles can be placed within the bag and retrieved from the bag without disturbing the vertical setting established by the user.

In accordance with another aspect of the present invention, a carry bag is vertically expandable by manipulating the gathers of the carry bag along a gathering element (e.g., the strap or elongated strap). The vertically expandable carry bag includes a shell having a lower margin and an upper margin spaced from the lower margin by a predetermined vertical rise of material. The shell defines an interior space for receiving items. A gathering channel can be formed by joining at least two layers of fabrics by a row of parallel stitches along the predetermined vertical rise of material of the shell. The space between the rows of stitches enables another material to freely move within this channel. An elongated strap has a first portion fully enclosed within the gathering channel and a second portion fully exposed from the gathering channel becoming a carry strap for handling by a user. The gathering channel in cooperation the strap cinches the material of the shell along the predetermined vertical rise thereof as the upper margin is slid along the first portion of the elongated strap toward the lower margin of the shell while the second portion of the elongated strap increases in the exact same length. Any gathers in the shell are released and the predetermined vertical rise is at least partially restored as the upper margin of the shell is slid along the exposed portion of the elongated strap.

In embodiments of the invention, the materials that are selected for the shell, the gathering channel, the gathering element, and the sewing criteria synergistically produce a vertically expandable carry bag that retains its level structure while it's vertical rise is easily adjusted by the user without the need for additional hardware and or external devices to support it's horizontal shape.

Thus, in accordance with a particular aspect of the invention, a vertically expandable carry bag can consist of only a shell, a channel and a flat, elongated strap slideably disposed in the channel. In this configuration, the shell has a lower margin and an upper margin spaced from the lower margin by a predetermined vertical rise of a material. The material of the shell comprises one or more fabric layers at least one of which defines an interior space for receiving items. The channel is defined by stitches disposed along the predetermined vertical rise of the material of the shell. The channel has a width, and the flat, elongated strap has a first portion disposed and enclosed within the channel and a second portion exposed from and outside of the channel which defines an adjustable length carry strap for handling by a user. The channel cinches the material of the shell along the predetermined vertical rise thereof as the upper margin is slid along the flat, first portion of the strap toward the lower margin of the shell while the second portion of the strap defining the carry strap increases in length, preferably, the exact same length as the decrease in length of the first portion. Any gathers in the shell are released and the predetermined vertical rise is at least partially restored as the upper margin is slid along the second portion of the elongated strap.

In another aspect, the invention concerns a cinching structure for use with a vertically expandable carry bag having a lower margin spaced from an upper margin by a vertical rise of a fabric material which includes an access to an interior space. A channel such as described already is disposed along the vertical rise of the fabric material, such as in the shell of the bag itself or as a separate element. The channel has a channel-width and presents an engagement surface made of a first material. A flat, elongated strap such as described already is made of a second material and sized so as to have a strap-width which is less than the channel-width. The strap has a first portion disposed within the channel so that the strap-width of the flat strap is in slideable engagement with the engagement surface and a second portion exposed from the channel and defining a carry strap for handling by a user. The first material and the second material frictionally engage one another so as to support, against the weight of the fabric material, the upper margin of the vertically expandable carry bag at an arbitrary slideable position along the vertical rise of the fabric material. The frictional engagement of the first and second material supports the upper margin at the arbitrary slideable position without regard to whether the access to the interior space is open or closed, and without regard to the weight of any contents within the bag.

A vertically expandable carry bag in accordance with further aspects of the invention comprises a shell, a channel, an elongated strap that cooperate, substantially as described in one of the foregoing paragraphs, to cinch the bag at a predetermined vertical rise, and further includes a fastener which has first and second complementary (mating) components. The first and second components being matingly engageable to one another. At least one of the components is disposed on the elongated strap and is operable so as to lock the upper margin of the shell in position relative to the second portion of the strap.

These and other advantages and features of the invention will be apparent from the accompanying drawing figures and description of certain embodiments thereof.

DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a perspective view of a backpack in accordance with the prior art;

FIG. 2 is a front plan view of a pouch in accordance with the prior art;

FIGS. 3 and 4 are perspective views of a tote in accordance with the prior art;

FIGS. 5-7 are a front plan view of a bag in accordance with the present invention shown with a top margin disposed at different positions along a carry strap;

FIG. 5A is the bag of FIG. 5 shown on a model;

FIG. 6A is the bag of FIG. 6 shown on a model having a longer torso than the model of FIG. 5A;

FIGS. 8-10 are a variation of the bag of FIGS. 5-7, now showing an adjustable strap loop length;

FIG. 9A illustrates a variation of the bag of FIG. 9 in which a loop adjustment mechanism is configured to have no free end.

FIGS. 11-13 are side views of another embodiment in accordance with the invention, shown at different vertical rises;

FIGS. 14-16 are front views of a third embodiment of a bag in accordance with the invention that uses the strap/channel gathering system of FIGS. 5-13;

FIGS. 17-19 are perspective views of a bag in accordance with the invention having optional, mating snaps that secure the bag in one or more cinched configurations;

FIG. 18A is a perspective view of a user carrying the bag of FIG. 18 with the snaps mated together;

FIG. 18B is a perspective view of a user carrying the bag of FIG. 18 with the snaps unattached;

FIG. 18C illustrates a perspective view of a user carrying a bag as in FIG. 18, but constructed so as to exhibit a preferred balance of design parameters;

FIGS. 20-22 illustrate various arrangements of the elongated strap from a bottom perspective view;

FIG. 23 illustrates a swatch of fabric from which samples can be cut for testing suitability for use in certain carry bags constructable in accordance with the invention;

FIG. 24A illustrates testing on the samples cut from the swatch of FIG. 23; and

FIGS. 24B and 24C illustrate testing on additional samples cut from other swatches.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENTS

As usual herein, “cinching” refers to the act of gathering material and is used to describe a shortening of the maximum length of a fabric panel. Gathers are the folds of fabric. The strap “cinches” the fabric by gathering it into a shorter length.

In the mature industry of bags, manufacturers and product development specialists have not been able to produce a vertically expandable carry bag without the use of additional hardware and or exterior devices to maintain the structural integrity that all successful bags require. However by selectively using specific materials and strap qualities, in conjunction with a suitable sewing construction as described herein, a vertically expandable carry bag can be achieved that retains its' shape by solely using the carry strap to adjust its' vertical rise while the carry bag is in use.

Referring now to FIGS. 5-7, a bag 10 in accordance with the present invention is illustrated. Bag 10 includes a shell 12 having a predetermined maximum volume as illustrated in FIG. 5. The shell comprises a panel of material stitched so as to define a predetermined vertical rise between a lower margin 13 and an upper margin 15. The shell also defines an interior space for receiving items. A channel 14 is defined along the vertical rise of the bag 10 by at least one stitch line sewn into the outside of shell 12. An elongated strap 16 has a first portion 18 and a second portion 19. The first portion 18 is disposed within channel 14, and is therefore hidden from view in the Figures. Second portion 19 is exposed from channel 14. Part of the exposed portion 19 forms a handle or carry strap for handling by a user.

The size of bag 10 can be changed by moving strap 16 with respect to channel 14, thereby causing the volume of bag 10 to vary from a maximum volume (see FIG. 5) to volumes less than the maximum volume (see FIGS. 6 and 7) to readily accommodate different contents placed within the bag while in use. In addition, the vertical rise of the bag can be changed by cinching the shell 12 along the length of the elongated strap 16. More particularly, the upper margin 15 can be positioned relative to the strap 16 so as to cinch the material of the shell about the first portion 18 of the strap 16 and thereby shorten the vertical rise of the bag. In other words, as the upper margin 15 is slid along the first portion 18 of the elongated strap toward the lower margin of the shell 12, concomitantly, the second portion 19, which defines the handle or carry strap, increases in length at a rate related to the shortening of the first portion (e.g., the same rate). Any gathers in the shell are released and the predetermined vertical rise is at least partially restored as the upper margin is slid along the second portion of the elongated strap.

Referring to FIG. 5A, the bag 10 of FIG. 5 is shown on the right side of a model, with the bag supported from the model's right shoulder. As in FIG. 5, the shell 12 of the bag is essentially uncinched so that the upper margin is spaced from the lower margin by the predetermined vertical rise of the material of the shell. For this model, the uncinched shell places the upper margin 15 just above her hip, a preferred placement for many people.

In FIG. 6A, the bag of FIG. 6 is shown on the right side of a model, suspended from the model's right shoulder, just as in FIG. 5A. The model in FIG. 6A has a comparatively longer torso than the model of FIG. 5A, yet the bag 10 can still be arranged to have the upper margin 15 just above the hip by cinching the shell 12 so as to expose more of the elongated strap and increase the amount of the section portion 19 that defines the carry strap. (Thus, enabling both body lengths to carry the same bag at the hip placement.)

Referring now to FIGS. 8-10, bag 10′ is illustrated in various shapes and volumes depending upon the contents within the bag and the user's handling preferences and/or requirements. Bag 10′ utilizes the elongated strap 16 as a part of the channel/cinching mechanism and also as the carry strap 19. Optionally, the elongated strap can extend around the bottom of the bag to support the contents of the bag. The carry strap 19 includes a mechanism 17 that permits the loop length of the elongated strap 16 to be adjusted.

As illustrated, the mechanism 17 can be a slider such as the D-ring slider illustrated in FIGS. 8-10. Alternatively, the loop length can be adjusted by different mechanisms including separable ends each fitted with complementary hook and loop fasteners or snaps. As another alternative to using sliders, the carry strap can comprise a belt and buckle a series of holes in the belt for receiving the buckle. In this configuration, the belt serves as the carry strap and any excess belt portion passes through the buckle and remains loose (unattached). The use of sliders is preferred, however, because the carry strap can be adjusted to an infinite number of lengths. The loop length adjustment permits the same person (as illustrated in FIG. 8-10) to selectively cinch the bag 10′ to different degrees (thereby shortening the vertical rise of the bag) while using the mechanism 17 to take up slack in the second portion 19. Consequently, a person can shorten the vertical rise of the bag 10′ to suit that person's needs yet wear the bag at the same location on her body. As well, the bag 10′ can be shortened and the mechanism 17 adjusted to shorten the carry strap 19 so that the bag can be carried in the hand like a purse. All of these carry methods can be easily accomplished while the bag is in use and secured to the user. As a result of the adjustment, a free end 19A lengthens as the loop is shortened, and vice versa.

In FIG. 9A, a variation of the bag 10′ of FIG. 9 is illustrated in which the bag 10″ has first and second mechanisms 17A, 17B arranged relative to the elongate strap 16 so that there is no longer a free end 19A on the carry strap 19. Instead, one end of the elongate strap is anchored to the mechanism 17A while an intermediate 16A portion of the elongate strap 16 passes through mechanism 17B and then through mechanism 17A and back to an anchor point at mechanism 17B. This arrangement has the elongated strap 16 passing through the channel 14 and around the bottom of the bag. Alternatively, however, the elongated straps 16′ can be provided, one in each channel 14, with the strap 16′ secured to the shell 12 generally near or at the bottom margin 13 of the bag 10″.

Other types of bags in accordance with the present invention may incorporate a similar type of strap/channel gathering system as shown in FIGS. 5-10. For example, referring now to FIGS. 11-13, a knapsack 20 is illustrated. Knapsack 20 has a shell 22 and a pair of channels 24 sewn into the outside of shell 22. A strap 26 has a portion extending through channel 24. As with bag 10, strap 26 is moveable with respect to channel 24 causing a predetermined vertical rise of the shell to vary from a maximum length (see FIG. 11) to any number of a plurality of shorter, cinched lengths which are less than the maximum length (see, e.g., FIGS. 12 and 13).

Referring now to FIGS. 14-16, a messenger bag 30 is illustrated using the same strap/channel gathering system of FIGS. 5-13.

Referring now to FIGS. 17-19, a tote bag 40 using a channeling technique is illustrated. Bag 40 includes a shell 42 and a plurality of channels 44 each comprising at least one stitch line in the material of the shell 42. Four strap segments 46 (two of which are hidden from view, and are therefore not shown) are placed within the channels 44. As illustrated in FIGS. 17-19, each strap segment 46 has one mating portion of a snap 48 connected to it. These snaps are preferably low-profile snaps so that each snap can easily travel through channel 44. However, those skilled in the art will readily recognize that the snaps could be of conventional size and the channel would have to be sized accordingly so that the snap can travel there through. Complementary, mating portions of the snap are connected to channel 44 at predetermined spaced apart locations so that the strap can be secured in place with respect to the channel in any of a number of positions as illustrated in FIGS. 17-19. These low-profile snaps are sold under the trade name FASGRIP®, which are commercially available from Fasnap of Elkhart, Ind. The use of snaps permits the vertical rise of the bag 40 to be adjusted and then secured into position.

In FIG. 18A, the snaps 48 have been engaged to provide a “neater” appearance than in FIG. 18B because the engaged snaps ensure equidistant spacing along the length of the shell 42 of the bag. In FIG. 18B, FIGS. 22 and 23, a bag 50, similar to the bag shown in Figure bag 40 has the snaps disengaged. In FIG. 18C, the bag 40′ exhibits a combination of materials in a bag construction that exhibits good wall stability, ease in the channel, and a flat carry strap slideably disposed in the channel with a frictional engagement suitable for retaining an arbitrary, vertically constrained position of the shell.

It should be apparent that the vertical adjustment and constraint of each of the bags illustrated herein and constructed in accordance with the invention can have the vertical adjustment made regardless of whether the bag is maintained in an open or closed state. Thus, for example, the bags of FIGS. 5-16 have an access near the top margin which can be opened or closed by using a draw cord, flap or zipper, and the bags of FIG. 16A-22 have an access without a closure mechanism. In each of these bag arrangements, a vertical adjustment can be made while the bag remains open or closed, and without changing the open/closed state of the bag.

For ease of illustration in the drawings, all channels have been shown on the exterior of the bag. However, one skilled in the art will readily recognize that the channels can also be sewn on the inside of the bag so that the cord loops or strap loops are disposed in the interior of the bag. The channel can be defined by parallel rows of stitches, or there can be a folded over and stitched edge at the side seam of the bag. It is currently preferred to place the channels on the inside of the bags so that the bags will have a less messy appearance and the straps or cord loops will not likely entangle with exterior objects. The channels themselves can be formed by stitching a row between the lining and the face of the bag, thereby creating a channel for the cinching material (e.g., cord or webbing). Alternatively, the channels can be joined to the side panels of the shell, thus forming the bag.

While the shell of the bag can comprise one or more fabric layers, the channel can be defined along the shell either with its own material, a combination of materials, or using the material of at least one of the plies of fabric. Thus, the channel can be defined by one or more rows of (preferably parallel) stitches between the plies of material of the shell. Presently, however, it is preferred that the channel be cut from material independent of the shell that forms the bag, with a channel-width defined by rows of stitches in the separate material. Optionally, the stitches that define the channel-width are the same stitches that attach the channel to the shell. The channel can have the separate material of the preferred embodiment on one or both sides of the channel-width, providing an engagement-surface which engages a gathering element (that is, a strap) that has been slideably disposed within the channel. The material used to define the channel can be the same material or a different material than that used for the gathering element. What is desired is that the frictional engagement between the gathering channel and the gathering element be sufficient to permit an upper margin of the shell to be arbitrarily locatable relative to the gathering element (strap) and to maintain its position thereat, against the weight of the fabric material that constitutes the shell. This can be accomplished by selecting the materials to be used and their relative sizes, as described further below.

Referring now to FIGS. 20-22, the elongated strap 16 has a first portion disposed within the channel 14, as previously noted, but now is shown from a bottom perspective in order to illustrate alternative arrangements of the elongated strap 16. Thus, in FIG. 20, the strap 16 is stitched at the side of the bag 60, proximate the lower margin by a box stitch 81 which secures the strap immovably to the shell 12. FIG. 21 illustrates strap 16′ and channel 14′ terminating at a base panel 83′ that is stitched in place at the bottom margin 13 of the bag 70. FIG. 22 has the strap 16 freely movable within the channel 14 about the bottom margin 13 of the bag 10.

As used herein, “gathers” refers to the mini-folds of fabric created next to a stitching line. The row of Gathers is called the gathering line. Gathers shorten the fabric at the stitching line as a function of the frequency and depth of the gathers. In general, some fabrics such as rayon jersey gather well, other fabrics such as cotton canvas gather poorly. “Well” refers to when the gathered folds of fabric are smooth and regular and the tension along the gathering line is even. Fabrics that gather poorly have folds that are bunched and irregular and the tension along the gathering line is uneven. Rigid fabrics can exhibit extreme bunching near the area of applied force.

A “gathering channel” comprises one or more layers of fabric joined by a row of parallel stitches. Thus a space between one or more rows of stitches allows another material to move freely within this channel. This other material is usually made of cord or webbing. We call this freely slideable material inside the gathering channel the “gathering element.” Note that the gathering channel refers to the inside ply of a multilayer fabric that defines the space when a multilayer fabric is used.

Because the gathering element is fully enclosed and therefore constrained by the gathering channel, the resulting lateral surface edge contact encourages the gathering element to remain flat and not twist or curl. This is especially important since the preferred embodiment for the gathering element is a webbing. The channel itself has a channel-width and the gathering element preferably has a width which is less than the channel-width, as described in detail below.

A “cinch” is the mechanical cooperation of the gathering channel and the gathering element. When the gathering channel is cinched along the gathering element, the gathering channel is compressed forming mini-folds which we have previously defined as “gathers.” The action of compressing the gathering channel by pulling against the gathering element is commonly called “cinching.” To cinch means to compress the fabric along the gathering channel by the action of the gathering element pushing against the length of the gathering channel. The material is “cinched” if there is no substantial release of the gathers so-formed.

“Wall stability” is the ability of a fabric plane to support its own weight vertically from the bottom, and to not bend. Wall stability is an important feature for selecting all bag fabrics. Fabrics with a high degree of wall stability are stiff and resist deformation from external forces. Fabrics with a low degree of wall stability are soft and droopy.

“Drapability” is the capacity of a fabric plane when compressed along a gathering channel under normal use to easily form mini-folds that are regular in frequency and depth. The gathered fabric plane decreases in length evenly along the gathering channel. The preferred term for high drapability fabrics is “pliable”.

“Resilience” refers to the ability of a fabric to recover from compression. The preferred term for high resilience is “springy;” the preferred term for low resilience is “limp.”

A fabric with good wall stability will maintain a carry bag's intended structure. A fabric with good drapability will help retain a carry bag's level vertical shape when cinched, by producing even and regular folds along the gathering channel. A fabric with good resilience will allow the carry bag to easily recover from a compressed state thus supporting the carry bag's vertical adjustments and level structure. Conversely, if the fabric is too stiff then when the carry bag is cinched, the compressive resistance will twist the bag out of shape. If the fabric is too soft, then when the carry bag is expanded from a compressed state, the carry bag will be pulled out of shape. In both cases the vertical level structure of the carry bag can have a distorted appearance. See FIG. 18B.

To successfully achieve a vertically expandable carry bag that retains its horizontal or “level” structure, materials should be selected so as to possess a balance among wall stability, drapability and resilience. A fabric that has great wall stability can be too stiff to form even gathers. A fabric that is highly drapable is usually too soft to have good wall stability and thus provide structural shell integrity. A fabric that has strong resilience will also have good wall stability, but is usually not pliable enough to form even and regular gathers along the gathering channel. What is needed is a synergistic combination of these qualities for my preferred selection of fabrics. A test that empirically gauges these qualities through hand-fabric manipulation has been developed. I call this test the “golden gatherable triangle.”

I define “fabric grains” as the direction of the linear weave of the fabric whereby the weave parallel to the running edge of the fabric roll (also known as the selvage) is called the “length grain” and the weave perpendicular to the selvage is called the “cross grain.” I test both grains because fabrics tend to have different handling properties depending on the orientation of their grains.

Referring to FIGS. 23 and 24A-C, the golden gatherable triangle test comprises cutting two triangles with a height of approximately 12 inches from a pre-selected fabric 90. The first triangle 92 is cut so that the height of the triangle is parallel to the fabric's length grains. The base of this triangle is the side that is perpendicular to the height of the triangle. A second triangle 94 is also cut with the same height from the test fabric, but now the height is parallel to the cross grains. The base of this triangle is also perpendicular to the height of this triangle. By compressing and releasing the bases of both triangles as we hold the cut pieces in the air (e.g., at room temperature and atmospheric pressure), we can test for good wall stability, good drapability and good resilience. Compression refers to squeezing the material in your hand at a location close to the base (e.g., ⅓ of the way up), as illustrated, so as to hold the width of the triangle within your closed hand, with the top of the triangle extending above your fist and the base extending below your fist.

FIG. 24A for example, shows a stiff fabric 92 that gathers poorly but has good wall stability. FIG. 24B shows a soft fabric 92′ that gathers well, but has poor wall stability and hence appears droopy. FIG. 24C shows a fabric 92″ that has good wall stability and good drapability. When the compressed fabric triangles are released from the hand and placed on a table, the ability of the test fabric triangles to recover at their bases to their original flat plane shape will reveal the fabrics' resilience qualities. These tests are performed on each of the two triangles that have been prepared for a given fabric.

Using the golden gatherable triangle test, we can pre-select appropriate fabrics and fabric grains that will support the structural horizontal integrity of the preferred vertically expandable carry bag embodiment.

The fabric choices for the shell and gathering channel can differ to some degree. Because the mini-folds created in the gathering channel are between two gathering stitch lines spaced relatively close to one another, a stiffer fabric can be used for the gathering channel thus supporting the level vertical rise adjustments of a softer fabric for the shell.

An additional fabric quality to test for the gathering channel and gathering element is the surface friction therebetween so that the elements cooperate to cinch the material at a given vertically constrained size. The “surface friction” is the coefficient of friction resulting from a mechanical force exerted on or against the surface of materials. Because the fabrics of the gathering channel are rubbing against the gathering element, they need to be relatively smooth. If the surfaces are too coarse, then the force applied when cinching the carry bag will not traverse evenly along the gathering channel causing the gathering channel and carry bag to bunch and twist.

If the surface friction between the cinching elements is too low then vertical slippage of the shell relative to the gathering element will occur. An appropriate surface friction for both the gathering channel and the gathering element is one that allows for vertical adjustments to be made to the shell without bunching or twisting in the gathering channel while still allowing for enough surface friction between the materials of the gathering channel and gathering element to exist. This enables a user-selected vertical rise of the shell to retain its adjusted position even if an unintended or a moderate force is applied. Moderate smoothness is the tactile value to strive for.

An excellent fabric choice for the shell and gathering channel that combines the exemplary material elements of wall stability, drapability, resilience, and desirable degree of surface friction is a jet laundered 200 denier nylon oxford weave fabric such as available under reference Yuma-Fco200uw from Brookwood Inc.

A level shaped, vertically-expandable carry bag preferably is constructed with regard to the stiffness of the gathering element and the “ease” within the gathering channel. It is the substantial collaboration of these two elements that enables the cinching of the gathering channel to maintain a vertically level upper shell margin while maintaining a pre-selected vertical rise intended by the user.

Now discussing the gathering element, cords are rarely used as a carry strap because their cylindrical shape concentrates the weight of a carry bag and its contents over a small surface area making it uncomfortable for the user. Cords do make great gathering elements because their cylindrical shape resists deformations of their outer wall allowing for a consistent transfer of force along the gathering channel resulting in even gathers. However, belts or webbing are preferred for the elongated strap, since the weight of the bag and its contents are spread over a larger surface plane. Webbing having a suitable width for a carry strap and having the desired property of carrying-comfort should be more than 1 inch wide. The ideal widths for moderate to large carry bags are between about 1.25 to about 2.25 inches.

Unfortunately, because these narrow materials are flat in shape, they tend to twist and curl in the gathering channel when lateral compressive force is applied. The deformation of the gathering element in turn causes twisting and bunching of the gathering channel resulting in a structurally deformed carry bag rather than an expandable level bag.

A highly stiff webbing or belt will resist bending at the edges but also will be uncomfortable to handle. Also highly stiff webbing or belt, of course, will have a higher coefficient of surface friction, and will result in bunching or twisting of gathers in the gathering channel and shell. A webbing that is comfortable to use as a carry strap and also has the appropriate surface friction for movement in the gathering channel is 825N webbing available from PK Supply Corp. Kent, Wash.

A sewing technique that will also help prevent twisting and curling of webbing or other narrow flat materials used for the gathering element is to completely stitch them across their entire width fuilly joining the gathering element with the fabrics used for the gathering channel. By joining these elements towards the bottom of the gatherable channel, as at 81 in FIG. 20, the shells' vertical rise capacity will not be substantially affected.

A further technique to help prevent the edges of the gathering element from bending is to add a bottom panel to the shell of the bag to completely join the width of the gathering element and the fabrics of the gathering channel and shell. See FIG. 21.

Another element to test for to achieve a level shaped vertically expandable carry bag is “ease” 14. The “ease” is the difference between the width of the gathering element and the width of the gathering channel. An accurate amount of ease within the gathering channel enables the gathering element to both move easily within the gathering channel and still have enough surface friction with the gathering channel so that the shell can be intentionally constrained at an arbitrary or predetermined vertical rise.

In testing webbing between 1 and 2.25 inches in width, the appropriate ease between the rows of stitches in the gathering channel was found to be between about 1.25 to about 3.125 inches. To determine the exact amount of ease for any particular combination of the cinching elements, adjusting for the material qualities of the gathering element such as thickness, surface friction, stiffness, and the material qualities of the gathering channel, one can readily sew a few test combinations. One can, for example, start testing for appropriate ease in the gathering channel by constructing the channel 0.125 inches greater than the gathering element's width.

The ease can be increased at intervals of 0.125 inches until there is enough ease in the channel to allow for unobstructed passage of the gathering element while enough contact between the gathering element and gathering channel remains to restrain the gathering channel and shell of the carry bag from collapsing under its own weight. A suitable case for the materials selected can thereby be determined without undue experimentation.

In tests using the previously disclosed fabric choice for the shell and gathering channel in conjunction with the previously disclosed preferred webbing at 2 inches in width, the ease necessary to accomplish level gathering cinching and resistance to vertical slippage was 2.375 inches.

An additional but not necessary technique to support the level shape of a vertically expandable carry bag is to join a narrow material that is both lightweight and stiff to the aperture of the shell. Testing for pliability, resilience, and surface friction material qualities is optional since, for such (that is, the opening of the bag) a shell, its width is negligible compared to its vertical length. By maintaining a narrow width relative to the length of the carry bag, the cinching elements are not affected and the relative weight of this material will not undermine the wall stability of the fabrics used in the gathering channel and shell.

In testing, I found an exemplary material that is both extremely lightweight and highly stiff in a low profile molded hook material, model No. HTH830, available from Velcro USA Inc., Manchester, N.Y. Widths of between 0.75 and 1.5 inches joined to the aperture of vertically expandable carry bag.

Another technique to increase the horizontal rigidity of a carry bag at the aperture without adding another element is to fold over and stitch the top edge of the shell fabric and gathering channel. Given the wall stability qualities of the fabrics chosen for the shell and gathering channel, this technique alone may be sufficient.

It is the synergistic use of the preferred embodiments and sewing techniques described which enable the creation of a vertically expandable carry bag that maintains its horizontal shape while its transport volume easily changes as the shopper's needs arise without the use of hardware and or external structures to achieve cinching of the shell along the carry straps. Furthermore, the changes in the bag's vertical volume are independent of the weight or volume of its contents enabling the user more choices of preferred shape. Also the bag's vertical adjustments do not depend on whether the bag is open or closed or even closable, which allows the user more handling choices.

Having described the presently preferred exemplary embodiment of a bag with variable volume in accordance with the present invention, it is believed that other modifications, variations and changes will be suggested to those skilled in the art in view of the teachings set forth herein. It is, therefore, to be understood that all such modifications, variations, and changes are believed to fall within the scope of the present invention as defined by the appended claims. 

1. A vertically expandable carry bag, consisting essentially of: a shell having a lower margin and an upper margin spaced from the lower margin by a predetermined vertical rise of a material, the material of the shell comprising one or more fabric layers at least one of which defines an interior space for receiving items; a channel defined by stitches along the predetermined vertical rise of the material of the shell and having a width; a flat, elongated strap having a first portion disposed and enclosed within the channel and a second portion exposed from and outside of the channel and defining an adjustable length carry strap for handling by a user, wherein the channel cinches the material of the shell along the predetermined vertical rise thereof as the upper margin is slid along the flat, first portion of the strap toward the lower margin of the shell while the second portion of the strap defining the carry strap increases in the exact same length, and wherein gathers in the shell are released and the predetermined vertical rise is at least partially restored as the upper margin is slid along the second portion of the elongated strap.
 2. A vertically expandable carry bag, comprising: a shell having a lower margin and an upper margin spaced from the lower margin by a predetermined vertical rise of material, the shell defining an interior space for receiving items; a channel defined along the predetermined vertical rise of the material of the shell; an elongated strap having a first portion disposed within the channel and a second portion exposed from the channel and defining a carry strap for handling by a user; and a fastener having first and second components, at least one of said components being disposed on the strap, the first and second components being matingly engageable to one another to lock the upper margin of the shell in position relative to the second portion of the strap, wherein the channel cinches the material of the shell along the predetermined vertical rise thereof as the upper margin is slid along the first portion of the strap toward the lower margin of the shell while the second portion of the strap defining the carry strap increases in the exact same length, and wherein gathers in the shell are released and the predetermined vertical rise is at least partially restored as the upper margin is slid along the second portion of the elongated strap.
 3. The bag of claim 2, wherein first portion of the strap is immovably secured relative to the shell at a location more proximate to the lower margin than the upper margin.
 4. The bag of claim 2, further comprising a bottom panel proximate the lower margin of the shell and wherein the first portion of the strap is secured to the bottom panel.
 5. The bag of claim 2, wherein the channel is defined by at least one row of stitches.
 6. The bag of claim 2, wherein the upper margin of the shell and the second portion of the elongated strap define a loop length and wherein the second portion includes at least one means for adjusting the loop length.
 7. The bag according to claim 2, wherein said shell is formed of at least one ply of material, wherein said channel is defined by at least one row of stitches in the fabric material by sewing said at least one ply to thereby form said channel to receive said strap.
 8. The bag according to claim 2, wherein the shell has an edge folded over onto itself and wherein the channel is formed by a row of stitches inside the folded over edge.
 9. The bag according to claim 2, further comprising an access proximate the upper margin of the shell and a means for closing the access configured to operate independently of the cinching of the material of the shell along the predetermined vertical rise.
 10. A cinching structure for use with a vertically expandable carry bag having a lower margin spaced from an upper margin by a vertical rise of a fabric material, the carry bag including an access to an interior space, comprising: a channel defined by stitches and being disposed along the vertical rise of the fabric material, the channel having a channel-width and presenting an engagement surface made of a first material; a flat, elongated strap of a second material sized so as to have a strap-width which is less than the channel-width, the strap having a first portion disposed within the channel so that the strap-width of the flat strap is in slideable engagement with the engagement surface, the strap having a second portion exposed from the channel and defining a carry strap for handling by a user, wherein the first material and the second material frictionally engage one another so as to support, against the weight of the fabric material, the upper margin of the vertically expandable carry bag at an arbitrary slideable position along the vertical rise of the fabric material, and wherein the frictional engagement of the first and second material supports the upper margin at the arbitrary slideable position without regard to whether the access to the interior space is open or closed.
 11. The cinching structure of claim 10, wherein the channel-width and the strap-width are selected with regard to the materials comprising the first and second materials.
 12. The cinching structure of claim 10, wherein the materials comprising the first and second materials are the same material.
 13. The cinching structure of claim 10, wherein the channel is defined by at least one row of stitches in the fabric material.
 14. The cinching structure of claim 10, wherein the second portion of the elongated strap defines a loop length above the upper margin of the shell and wherein the second portion includes at least one means for adjusting the loop length.
 15. The cinching structure of claim 10, wherein the shell comprises at least two plies of material and wherein the channel is defined between two of the plies.
 16. The cinching structure of claim 10, wherein the channel and strap are slidably movable relative to one another independent of any closure provided on the carry bag. 